I recently got a comment from one of our readers having problems accessing Office 2007 after upgrading to Windows 8.
Doing some digging on the web, it seems that various users are having the same problem: They performed an upgrade to Windows 8 Pro or core edition and then suddenly they lost the ability to open Word, Excel, PowerPorint, etc., even after trying re-enter their valid product key, the software will respond with a message telling the user that the product key is invalid.
If you are having the same or related problem, you should consider picking up the phone and calling Microsoft Support and doing an activation by phone.
Key in mind the terms for the license:
Microsoft Office Activation Number: http://support.microsoft.com/kb/950929
Activate Microsoft Office 2007 programs http://office.microsoft.com/en-us/sharepoint-designer-help/activate-microsoft-office-programs-HA001233434.aspx
(See activation by phone) Older version of Office: Activation and registration of a Microsoft product http://support.microsoft.com/?kbid=326851
Invalid product key type errors occur in Microsoft Office 2007 or 2003 http://support.microsoft.com/kb/2549291
Activate by using the telephone You can telephone an Activation Center and activate your product with the help of a customer service representative.